A focus-adjustment signal generating apparatus includes a filter to extract a high-frequency component at a specific frequency or higher from a luminance signal of an input video signal, a comparator to compare an absolute value of the high-frequency component with a specific reference value, to output a first detection signal when the absolute value is equal to or larger than the reference value whereas a second detection signal when the absolute value is smaller than the reference value, an extender to extend an output period of the first detection signal according to a period indicated by a period-length setting signal, to output an extended first detection signal, and a selector to select a first chrominance difference signal indicating a specific color in response to the extended first detection signal whereas a second chrominance difference signal indicating an achromatic color in response to the second detection signal, the first or the second chrominance difference signal being output as a focus-adjustment signal.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An imaging apparatus comprising: a video signal generator configured to take an image of an object and generate a video signal carrying the image; a filter configured to extract a high frequency component at a specific frequency or higher from a luminance signal of the video signal; a comparator configured to compare an absolute value of the high-frequency component with a specific reference value, to output a first detection signal when the absolute value is equal to or larger than the reference value whereas a second detection signal when the absolute value is smaller than the reference value; a selector configured to select a first chrominance difference signal indicating a specific color in response to the first detection signal whereas a second chrominance difference signal indicating an achromatic color in response to the second detection signal, the first or the second chrominance difference signal being output as a focus-adjustment signal; a down converter configured to down-convert the focus-adjustment signal by decreasing at least either the number of lines in a vertical direction or the number of pixels in a horizontal direction of the focus-adjustment signal; a display configured to display an image of the object with the specific color at an edge portion of the image; a peak detector configured to detect a peak level of the luminance signal; a block-average calculator configured to calculate an average of the peak level in blocks of the image; and an arithmetic unit configured to perform a specific operation to the peak level and the average to obtain the reference value.
2. The imaging apparatus according to claim 1 further comprising an iris mechanism configured to control an amount of an incident light of the object based on the peak level.
3. An imaging method comprising the steps of: taking an image of an object and generating a video signal carrying the image; extracting a high-frequency component at a specific frequency or higher from a luminance signal of the input video signal; comparing an absolute value of the high frequency component with a specific reference value, to output a first detection signal when the absolute value is equal to or larger than the reference value whereas a second detection signal when the absolute value is smaller than the reference value; selecting a first chrominance difference signal indicating a specific color in response to the first detection signal, whereas a second chrominance difference signal indicating an achromatic color in response to the second detection signal, the first or the second chrominance difference signal being output as a focus-adjustment signal; down-converting the focus-adjustment signal by decreasing at least either the number of lines in a vertical direction or the number of pixels in a horizontal direction of the focus-adjustment signal; displaying an image of the object with the specific color at an edge portion of the image; detecting a peak level of the luminance signal; calculating an average of the peak level in blocks of the image; and performing a specific operation to the peak level and the average to obtain the reference value.
4. The imaging method according to claim 3 further comprising the step of controlling an amount of an incident light of the object based on the peak level.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
May 31, 2011
January 29, 2013
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